1. Field of the Invention
The present invention relates to a valve having relatively movable disk members each with a fluid opening which can be brought into and out of fluid conducting alignment for discharging fluid to a discharge port, and, more particularly, to improvements to such a valve which include a discharge port downstream of the disks formed by a sleeve anchored to the valve body.
2. Description of the Prior Art
This invention relates to a valve having a stationary disk and a rotatable disk mounted in a valve housing in a face-to-face confronting relationship in a pathway for fluid in a valve body. The disks are each provided with at least one orifice or opening to control the flow of fluid through the valve by the size of the holes in the disk as well as the degree of alignment between the holes in the disk. Angular movement of one disk relative to the other in the valve body is accomplished by turning a handle situated outside of the valve body but coupled to produce rotation of the rotatable disk. The rotatable disk can be moved from a full open position wherein the hole or holes in one disk align with the hole or holes in the other disk for providing maximum flow through the valve to a fully closed position wherein the hole or holes in the respective disks are misaligned and blocked by solid portions of the confronting disks.
Valves of this type are particularly useful for controlling the flow of fluids from oil and gas wells and the like. Such a valve is used to control the rate of flow of well production fluids that may contain abrasive containments such as sand particles. Such fluid when entering the valve can be under extreme pressure of the order of, for example, 3000 PSI. The openings in the disks are of a smaller cross-sectional area than either an upstream entry chamber or a downstream discharge chamber that are formed in a valve body. The flow restriction formed by the opening in the disks cause an acceleration of the fluid passing through the openings. The increase to the velocity of the fluid emerging from the opening in the downstream disk enters a discharge chamber which has a cross-sectional area that is greater than the cross-sectional area of the openings in the downstream disk. Because of the construction of the discharge chamber, particularly when formed by a renewable sleeve in the valve body, a large pressure drop in the fluid passing through the sleeve is created. The effect is to reduce the capacity of the valve, and, because of the construction of the removable sleeve, abrupt changes to the configuration of the opening in the sleeve produce turbulence in the fluid, particularly at the outlet of the valve which is unprotected by the renewable sleeve.
In the known form of valves of the type under discussion, the outlet is defined by an oblong transverse configuration immediately downstream of the downstream disk. The oblong configuration is a result of the need to provide openings to receive retainer pins which are used to anchor the disk in the valve body. The area of the oblong configuration is reduced by the thickness of the sleeve when such a protective sleeve is required for the outlet chamber. The reduced oblong area of the sleeve, in turn limits the maximum size of the disk that can be used with the renewable sleeve as compared with, for example, the size of the oblong outlet chamber when a removable sleeve is not used. The smaller volume for conducting fluid in the sleeve creates a larger pressure drop to the fluid passing through the sleeve, and thus reducing the capacity of the valve.
Moreover, in the known form of valves using renewable sleeves at the outlet chamber, the sleeve is adhered to the valve body by an adhesive, such as epoxy cement, which also is relied upon to prevent the flow of fluid between the sleeve and the valve body. When it is necessary to replace the sleeve, the valve body must be heated to a temperature sufficient to soften the epoxy so that the sleeve can be removed. Typically, it is known to heat a valve body to over 250 degrees Fahrenheit in order to effectively soften the epoxy for replacement of the sleeve.